The invention concerns a pipeline or duct switch for selectively connecting a loading conduit to one of several secondary conduits.
Such conduits may be plastics or flexible metal hoses which provide external protection and a guide for a cable in the form of a flexible wire axially movable within the conduit. A switch of this kind is required for precise mutual positioning of the conduits to be connected end to end, i.e. high-precision alignment, rather than sealing tightness of the connection, which is of secondary importance. Medical and radiation technology is a typical field of application of such a switch; for in these fields, radiation sources have frequently to be guided to a particular location with high accuracy. In the context of radiation technology it must constantly be ensured that a radiation source is not damaged in a conduit or even comes out of a conduit into an unprotected environment. This risk is present above all when several conduits to be connected to a single conduit can be selectively coupled to the pipeline switch and uncoupled from it.
The distribution of rays obtainable at the object of irradiation, e.g. in interstitial or intracavity tumor therapy, only covers a region of volume which is defined by the length of the hollow probe and the depth of penetration of radiation, and which consequently has essentially a linear dimension. Three-dimensional distribution of radiation can therefore be obtained only with several radiation sources. In addition, so-called afterloading devices may have available to them several pipes, radiation sources, radiation shielding bodies and applicators, or after each irradiation process in an applicator the connecting hose must be uncoupled from the afterloading device and the connecting hose of the next applicator coupled on.
Multi-pipe devices are, for technical reasons, limited to three or six pipes and, according to the number of pipes, very expensive. They cannot likewise be operated fully automatically for applications with more than six applicators, such as e.g. in the case of irridation of neck tumors and breast cancer, if the number of applicators required exceeds the number of pipes. Changing the hoses from applicator to applicator each time with a single-pipe device is, on the other hand, very time-consuming and inconveniences the patient.